boost/iostreams/detail/double_object.hpp

   1 // (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
   2 // (C) Copyright 2004-2007 Jonathan Turkanis
   3 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   4 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
   5
   6 // See http://www.boost.org/libs/iostreams for documentation.
   7
   8 // Contains the definition of the class template
   9 // boost::iostreams::detail::double_object, which is similar to compressed pair
  10 // except that both members of the pair have the same type, and
  11 // compression occurs only if requested using a boolean template
  12 // parameter.
  13
  14 #ifndef BOOST_IOSTREAMS_DETAIL_DOUBLE_OBJECT_HPP_INCLUDED
  15 #define BOOST_IOSTREAMS_DETAIL_DOUBLE_OBJECT_HPP_INCLUDED
  16
  17 #if defined(_MSC_VER) && (_MSC_VER >= 1020)
  18 # pragma once
  19 #endif
  20
  21 #include <algorithm>              // swap.
  22 #include <boost/detail/workaround.hpp>
  23 #include <boost/mpl/if.hpp>
  24 #if BOOST_WORKAROUND(__MWERKS__, > 0x3003)
  25 # include <msl_utility>
  26 #else
  27 # include <boost/call_traits.hpp>
  28 #endif
  29
  30 namespace boost { namespace iostreams { namespace detail {
  31
  32 template<typename T>
  33 class single_object_holder {
  34 public:
  35 #if BOOST_WORKAROUND(__MWERKS__, > 0x3003)
  36     typedef Metrowerks::call_traits<T>             traits_type;
  37 #else
  38     typedef boost::call_traits<T>                  traits_type;
  39 #endif
  40     typedef typename traits_type::param_type       param_type;
  41     typedef typename traits_type::reference        reference;
  42     typedef typename traits_type::const_reference  const_reference;
  43     single_object_holder() { }
  44     single_object_holder(param_type t) : first_(t) { }
  45     reference first() { return first_; }
  46     const_reference first() const { return first_; }
  47     reference second() { return first_; }
  48     const_reference second() const { return first_; }
  49     void swap(single_object_holder& o)
  50     { std::swap(first_, o.first_); }
  51 private:
  52     T first_;
  53 };
  54
  55 template<typename T>
  56 struct double_object_holder {
  57 public:
  58 #if BOOST_WORKAROUND(__MWERKS__, > 0x3003)
  59     typedef Metrowerks::call_traits<T>             traits_type;
  60 #else
  61     typedef boost::call_traits<T>                  traits_type;
  62 #endif
  63     typedef typename traits_type::param_type       param_type;
  64     typedef typename traits_type::reference        reference;
  65     typedef typename traits_type::const_reference  const_reference;
  66     double_object_holder() { }
  67     double_object_holder(param_type t1, param_type t2)
  68         : first_(t1), second_(t2) { }
  69     reference first() { return first_; }
  70     const_reference first() const { return first_; }
  71     reference second() { return second_; }
  72     const_reference second() const { return second_; }
  73     void swap(double_object_holder& d)
  74     {
  75         std::swap(first_, d.first_);
  76         std::swap(second_, d.second_);
  77     }
  78 private:
  79     T first_, second_;
  80 };
  81
  82 template<typename T, typename IsDouble>
  83 class double_object
  84     : public mpl::if_<
  85                  IsDouble,
  86                  double_object_holder<T>,
  87                  single_object_holder<T>
  88              >::type
  89 {
  90 private:
  91     typedef typename
  92             mpl::if_<
  93                 IsDouble,
  94                 double_object_holder<T>,
  95                 single_object_holder<T>
  96             >::type                                base_type;
  97 public:
  98 #if BOOST_WORKAROUND(__MWERKS__, > 0x3003)
  99     typedef Metrowerks::call_traits<T>             traits_type;
 100 #else
 101     typedef boost::call_traits<T>                  traits_type;
 102 #endif
 103     typedef typename traits_type::param_type       param_type;
 104     typedef typename traits_type::reference        reference;
 105     typedef typename traits_type::const_reference  const_reference;
 106     double_object() : base_type() {}
 107     double_object(param_type t1, param_type t2)
 108         : base_type(t1, t2) { }
 109     bool is_double() const { return IsDouble::value; }
 110 };
 111
 112 } } } // End namespaces detail, iostreams, boost.
 113
 114 #endif // #ifndef BOOST_IOSTREAMS_DETAIL_DOUBLE_OBJECT_HPP_INCLUDED